The invention relates to reflective optical elements for a dynamic deflection of a laser beam and to a manufacturing method for these reflective elements. Such reflective elements are typically also called scanner mirrors which can be pivoted about at least one axis by means of a drive. A laser beam incident onto the reflective surface is reflected in dependence on the angle of incidence and can be correspondingly deflected by the pivoting and in so doing, for example, the focus of the laser beam can be deflected one-dimensionally or two-dimensionally for a processing. It is obvious in this respect that high accelerations act on a scanner mirror on the pivoting since high deflection speeds of the laser beam are desired. A reduced deadweight of the moved part of such a reflective element with a correspondingly small mass moment of inertia is therefore an important parameter to be observed.
Further demands on these elements which reflect laser radiation are high degrees of reflectance (reflectivity) for the radiation, good heat conduction and sufficient thermal resistance, mechanical strength and stiffness, which should be observed for as long-lasting a time as possible.
Scanner mirrors have to date been manufactured using aluminum, beryllium, silicon or silicon carbide. The volumes to be produced are limited and large batch sizes do not occur in this respect. Metallic base bodies are typically used which have a surface which reflects the laser radiation. The base bodies have different geometrical designs due to the above-named required properties. Cooling fins are present, for example, to allow a cooling to a tolerable temperature. The manufacture of such base bodies normally does not produce any larger problems. However, since a high reflectance is required at the reflective surface, an extremely complex and/or expensive surface machining has to be carried out at the reflective surface which has previously only been achievable by a chipping machining. An example for such a machining is glaze milling. However, this mechanical processing substantially determines the level of the manufacturing costs. A further disadvantage moreover occurs through this machining. It is namely not possible to produce such a single-part reflective element using the known technical means. For this reason, at least always two parts, namely a reflective part which is already well polished or which can be easily polished and a holder for receiving a drive shaft, have to be connected to one another. An adhesive connection is usually selected for this whose thermal resistance and service life are problematic, however. The observation of high precision is additionally required in this joining step since the two parts have to be adjusted very precisely with respect to one another.
Such a two-part design can also not be geometrically designed in an optimized form since there are construction and technical joining restrictions.